Microsoft Graph - List apps in chat - 404 UnknownError

Hello Sayali-MSFT​ 

Thanks for your quick answer and these insights.

Would you mind sharing an official documentation mentioning this restriction or improve the official documentation to mention this?

All the related pages from the Microsoft Graph documentation says things like "Note: If the chat is associated with an onlineMeeting instance, then, effectively, the teamsApps installed in the meeting will be listed."
18 occurences of this note according to a GitHub Code search and nothing explaining that this is only available to Microsoft-internal or preview tenants.

Furthermore, there is a 4 years old article in the official Microsoft Azure Medium blog, written by a Software Engineer at Microsoft explaining how you can add an app to a Teams meeting using these APIs: Adding Custom App to Microsoft Teams Meeting Using Microsoft Graph APIs. | by Manish Saluja | Microsoft Azure | Medium. How can this article have been up for so long if these APIs are not really available?

Can you share the plans around these APIs to make them available for external developers?

Thanks again